JPH04341508A - Production of coupling formed body for different kinds of materials - Google Patents

Abstract

PURPOSE:To easily produce a formed body of functionally gradient material coupling structure having a good joined interface and with the characteristics of the metallic materials different from each other by forming a powder-filled bad with the metal composition changing stepwise from one material to he other material between the different kinds of metallic materials and extruding the resulting material. CONSTITUTION:The first member (e.g. magnetic material) and second member (e.g. nonmagnetic material) of the different kinds of metallic materials and metal powders 1 and 3 respectively having the same composition are filled in a highly workable metallic vessel 4. A powder 2 obtained by appropriately mixing the powders 1 and 3 is filled between the powders 1 and 3, and a functionally gradient material region (>= about 5mm thick) consisting of the mixed powder bed with the composition changing stepwise from the powder 1 to the powder 3 is formed. The resulting material is then presintered at about 50-90% of the solidius, hot-extruded. A formed article of coupling structure for different kinds of metallic materials is easily obtained in this way.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing joint molded bodies for dissimilar materials. Specifically, the present invention provides dissimilar materials, that is, two types of metal materials with different metal material properties,
For example, a method for manufacturing a joint molded body between metal materials with a large difference in hot deformation resistance and a large coefficient of thermal expansion, such as combinations of magnetic materials and non-magnetic materials, corrosion-resistant materials and high-strength materials, heat-resistant materials and high-toughness materials, etc. Regarding.

0002

2. Description of the Related Art Metal materials such as rods and tubes are required to have different material properties depending on the usage environment or location. For this reason, dissimilar metallic materials are sometimes used simultaneously as so-called multifunctional metallic materials, and joint joining of dissimilar metallic materials is required to assemble them integrally.

[0003] Particularly in recent years, the properties required of metal materials have become more diverse and stricter. Such dissimilar metal materials have problems such as difficulty in joining by welding or threaded joints, and insufficient joint strength, which limits the spread of multifunctional metal materials. Under these circumstances, there is a need for improvements in joint structures of dissimilar metal materials.

For example, in the field of oil wells, different metal materials with different material properties are sometimes used for underground electromagnetic wave communication, but since it is difficult to join them together, threaded joints are used.

[0005] Conventionally, methods for joining metal materials such as rods and pipes generally include joining by welding or joining by tightening screws. However, this joining method cannot be applied to some materials that have a large difference in coefficient of thermal expansion or cannot be machined.

Therefore, for example, Utility Model Application No. 62-141985
As disclosed in the above publication, there is a method of fitting and metallurgically joining using the difference in thermal expansion coefficients, but with this method, there is a possibility that unjoined portions remain.

On the other hand, a method for manufacturing a clad metal tube using metal powder is disclosed in, for example, Japanese Patent Laid-Open No. 18456/1983. However, although the clad metal tube thus obtained is effective as a method for joining dissimilar materials in the thickness direction, it cannot be applied as a so-called joint for joining in the axial direction.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a joint structure for dissimilar metal materials and a method for manufacturing the same, which generally has a good gradient function of material properties at the joint interface. It is to be.

A more specific object of the present invention is to provide a joint tube or rod for dissimilar metal tubes or rods, which has sufficient joint strength and whose metal material properties change continuously or stepwise in the longitudinal direction. An object of the present invention is to provide a manufacturing method.

0010

[Means for Solving the Problems] As a result of various studies to solve the above problems, the present inventor has found that (1) a joint with a so-called inclined function is effective as a joint structure for dissimilar metal materials; and (2) It was discovered that the production of functionally graded joints for dissimilar metal materials by integral molding is possible using powder metallurgy.

[0011] Therefore, as a result of research into a manufacturing method using integral molding processing using powder metallurgy for joints made of dissimilar metal materials with functionally graded characteristics, we found that the conventional powder metallurgy method, which provides a good joint interface for clad metal pipes, However, during hot extrusion molding, the metal flow in the axial direction varies depending on the material, so it may not be possible to obtain a sufficient bonding interface. The present invention was completed based on the finding that even large differences in hot deformability and thermal expansion coefficient can be easily achieved under specific conditions.

Accordingly, the present invention, in its broadest sense, is a joint structure for dissimilar metal materials comprising a hot extrusion molded product of a powder-filled bed in which the metal composition is changed stepwise or continuously.

More specifically, the present invention provides a method for manufacturing a joint molded body for a first member and a second member that are made of different materials, wherein A joint for dissimilar materials characterized by forming a powder-filled layer having a metal composition that changes stepwise or continuously to a second metal composition that is the same or similar to that of two members, and then extruding the powder-filled layer. This is a method for manufacturing a molded object.

In a preferred embodiment of the present invention, the molded body is a rod or a tube, and the metal composition thereof changes continuously or stepwise in the axial direction.

It is effective when the hot deformation resistance ratio between the first metal composition and the second metal composition is 1.5 or more, and the solidus temperature of the first metal composition and the second metal composition is It is preferable to perform hot extrusion molding by heating the entire first member powder-filled layer and the second member to a temperature from 70% or more of the lower solidus temperature to below the solidus temperature.

Furthermore, the powder-filled layer has a three-layer structure of a first metal composition, a second metal composition, and a mixed metal composition of these first and second metal compositions, and the thickness of the filled layer made of the mixed metal composition is may be set to 2 mm or more.

[0017]

[Operation] Next, the operation of the present invention will be explained.

1 to 3 are schematic illustrations of a mode of carrying out the method according to the invention, in which identical parts are designated by the same reference numerals in each figure.

First, the dissimilar metal materials having different metal material properties in the present invention include magnetic materials such as carbon steel, low alloy steel, ferritic stainless steel, and martensitic stainless steel, and austenitic stainless steel and Ni-based high alloy. combinations with non-magnetic materials such as Ni-based high alloys, combinations of corrosion-resistant materials such as Ni-based high alloys with high-strength materials such as martensitic stainless steel and Co-based high alloys, and combinations of heat-resistant materials such as Ni-based high alloys with low alloys. A combination of steel, carbon steel, and ferritic stainless steel may be considered.

In FIG. 1, a metal container 4 is filled with metal powders 1 and 3 having the same or similar metal compositions to the first member and second member (both not shown) made of dissimilar metal materials, respectively. The boundary is filled with an appropriate mixed powder 2 of metal powders 1 and 3. In this way, from the metal powder 1 having the same or similar metal composition as the first member to the metal powder 3 having the same or similar metal composition to the second member,
In the illustrated example, a powder-filled layer having a metal composition that changes stepwise in two steps is formed.

In the present invention, the chemical composition of the bonding surface is continuously changed in the axial direction as described above by converting a metal material with a large difference in hot deformation resistance and thermal expansion coefficient into a functionally graded material. This is to avoid concentration, and the functionally graded material region is preferably 5 mm or more.

[0022] This is applied to the combination of metal materials with a hot deformation resistance ratio of 1.5 or more because when the deformation resistance ratio at the hot extrusion processing temperature is less than 1.5, there is no functionally graded material region. Although sufficient bonding strength can be obtained even if the deformation resistance ratio at that temperature is 1.5 or more, if there is no functionally graded material region, pores will be generated on the bonding surface due to the difference in metal flow.

[0023] Here, "hot deformation resistance ratio" is the deformation resistance inherent to the metal material at the hot forming temperature, that is, the ratio of the deformation resistance of the first member and the second member at the hot forming temperature. . It varies greatly depending on temperature, strain rate, and material. Therefore, the hot deformation resistance ratio referred to here is the difference in deformation resistance ratio between materials at the same strain rate and extrusion temperature. For example, at 1100°C and strain rate of 10-1 sec, low alloy steel has a deformation resistance ratio of 8 kg/mm2. , stainless steel is 16k
Since the deformation resistance is g/mm2, the hot deformation resistance ratio is 2
．． It is 0.

[0024] The powder-filled bed is provided in a metal container with good workability, and this metal container with good workability is made of iron, iron,
The wall thickness of the container is preferably 1 to 4 mm using a metal that has good malleability at room temperature and hot extrusion processing temperature, such as carbon steel, alloy steel, and stainless steel. This is because during the hot extrusion process, contact between the die and the mandrel occurs in the metal container, and the hot malleability of the metal container affects the formability of the extruded product.

Next, for example, as a method for filling the mixed powder between the metal material powder A and the metal material powder B, the volume ratio of the metal material powder A and the metal material powder B is A:B=20.
:80 to A:B = 80:20, or the mixing ratio of metal material powder A and metal material powder B is changed stepwise to fill the powder almost continuously in the axial direction in a layered manner. That's good. At this time, the thickness of the mixed powder layer is 2 mm.
The above is desirable. The reason for this is that metal flow differences occur during hot extrusion processing, but if these filling methods are not satisfied, pores will be generated at the joint surface.

After filling the metal powder into the metal container 4 in this way, the inside is degassed through the degassing pipe 5. At this time, at a vacuum level of 1 x 10-1 mmHg or higher,
A vacuum degassing treatment in which the temperature is maintained at a temperature up to 00°C for 10 minutes or more is desirable. This is to efficiently remove adsorbed gas and water on the powder surface, thereby improving the quality of the product. After degassing, the degassing pipe 5 is sealed.
It is desirable that the sealing be performed in a vacuum state to avoid air intrusion into the pores of the degassing tube 5.

[0027] The powder billet is heated before hot extrusion molding, and the method for this is soaking in an electric furnace or gas furnace, or high-frequency induction heating, which can heat the billet to the holding temperature in a short time by rapid heating. good. At this time,
In order to perform high-frequency induction heating smoothly, the powder billet is pre-sintered at 50 to 90% of the solidus temperature of the metal material, or the powder billet is cold isostatically pressed before high-frequency heating. Powder packing relative density is 7
It is necessary to set it to 5% or more to reduce the non-uniformity of the temperature distribution of the powder billet during high-frequency induction heating.

The reason why the heating temperature before hot extrusion is limited from 70% or more of the solidus temperature of the metal material to below the solidus temperature is because the metal material This is because the deformation resistance of the powder increases, making it difficult for the metal material powder to undergo plastic deformation, resulting in it not being able to be extruded and becoming clogged in the middle, or being unable to maintain formability even if it is extruded. Furthermore, if the solidus temperature is exceeded, some parts may melt and segregation may occur, making it impossible to obtain rods and tubes with good formability.

[0029] Here, the "solidus temperature" refers to the one having the lowest solidus temperature among the alloy components constituting the metal powder. All alloy materials have a solidus (the temperature at which parts of the material begin to melt) and a liquidus (the temperature at which the entire material finishes melting). The temperature of this solidus line and liquidus line differs greatly depending on the components. Therefore, the solidus line referred to here is the temperature at which microscopic partial melting begins.

The metal container covering the surface of the metal material is preferably removed by pickling or machining. Further, if necessary, it is desirable to perform heat treatment after hot extrusion molding to impart properties suitable for the usage environment.

FIGS. 2 and 3 show an example of manufacturing a metal pipe joint, in which a metal pipe 9 having concentric double pipe walls is used instead of the metal pipe 4. metal powder 6,
A mixed powder layer 7 is provided at the boundary of 8, but in the illustrated example, this mixed powder layer 7 is further multi-layered, and the powder composition is slightly changed in each layer, so that the entire mixed powder layer 7 has a slope. The powder composition is made to change depending on the temperature. The degassing and sealing operations using the degassing tube 10 are the same as those shown in FIG. In this case, the total of the mixed powder layers 7, which are multi-layered, is 2 m.
It is preferable that the thickness be 1 m or more.

FIG. 3 shows an example in which the metal powder shown in FIG. 2 is multi-functionalized by changing several types of metal composition.
Metal composition: metal powder 11, metal powder 13, metal powder 15
The mixed powder layers 12, 14, and 16 each have an independent function, and the metal composition between them changes in a gradient manner. By creating multiple stages in this way, a multifunctional tube can be manufactured. It is preferable that each mixed powder layer has a thickness of 2 mm or more.

The mixing ratio of each metal powder, the thickness of each metal powder layer, etc. may be determined depending on how to incline the metal properties, and can be appropriately determined by a person skilled in the art based on the above explanation.

[0034] The functionally inclined joint pipe (rod) manufactured in this way is further joined to a mating member by cutting a thread at the end or by welding, if necessary, and used as a joint. .

[0035]

[Example 1] In this example, the illustrated dimensions (mm
) was extruded into a rod-shaped joint.

Water atomized powder 1 having the chemical composition of sample A in Table 1 (average particle size 250 μm or less) was filled into the low carbon steel container 4 shown in FIG. N2 gas atomized powder (average particle size 250 μm or less) containing the powder of sample A and the chemical composition of sample B was mixed for 30 minutes.
: Powder 2 mixed at a volume ratio of 70 to 70:30 to 1 to
Fill the powder to a height of 10 mm, then fill the powder of sample B in Table 1 on top of this mixed powder 2, and then
It was vacuum degassed at 10-2 mmHg for 1 hr at room temperature and sealed to form a powder billet.

[0037] This powder billet was charged into a gas heating furnace and heated to 1200°C, and then molded using a Eugene hot extruder at an extrusion ratio of 10 and an extrusion temperature of 1150°C to produce a functionally graded metal rod. .

The resulting bar was machined to remove the low carbon steel vessel. Table 2 shows the joint characteristics of the rod obtained in this way.
Test Run No. 1 to 5 and Run No.
10 and 13.

[0039]

[Example 2] In this example, the illustrated dimensions (mm
) tubular fittings were extruded.

N2 gas atomized powder 6 (500 μm or less) having the chemical composition of sample C in Table 1 is filled into the low carbon steel container 9 shown in FIG. and Ar gas atomized powder (500 μm or less) of chemical components of sample D at 4:1, 3:2, 2:3,
Powder 7 mixed at a ratio of 1:4 is filled in a layer with a total height of 4 mm, 1 mm apart from the bottom, and the powder of sample D in Table 1 is further filled on top of this mixed powder 7, and the degassing tube 10 is filled.
1 x 10-2 mmHg vacuum degassing at 400 °C x
The tube was sealed for 30 minutes.

A portion of this powder billet was pressurized to 4,000 atmospheres by cold isostatic pressing to increase the powder packing density. This powder billet was preheated to 800 °C in a rotary gas furnace, followed by an additional 1
After heating to 200° C. in a high frequency induction heating furnace, a tube was produced by molding using a Eugene hot extruder at an extrusion ratio of 7 and an extrusion temperature of 1150° C.

For other powder billets, 1
After heating to 000 to 1200°C, the tube was molded using a Eugene hot extruder at an extrusion ratio of 7 and an extrusion temperature of 950 to 1150°C.

The tube thus obtained was machined to remove the low carbon steel container. Table 2 shows the joint characteristics of the pipes obtained in this way. Shown in 6 to 8.

[0044]

[Example 3] In this example, the illustrated dimensions (mm
) tubular fittings were extruded.

Water atomized powder 11 (250 μm or less) having the chemical composition of sample A in Table 1 is filled into the low carbon steel container 18 in FIG. Powder 12, which is a 50:50 mixture of Ar gas atomized powder (500 μm or less) having the chemical components of sample D, was filled to a height of 5 mm, and on top of this mixed powder 12, samples of sample D in Table 1 were placed. Fill with powder 13.

This filling method is repeated. That is, 5 powders of sample A and sample D are placed on top of powder 13.
Powder 14 mixed at a ratio of 0:50 is filled to a height of 5 mm, and powder 15 of sample A is filled on top of mixed powder 14. Furthermore, powder of sample A and sample B are placed on top of powder 15.
Powder 16, which is a 50:50 mixture of N2 gas atomized powder (250 μm or less) with the chemical composition of
The sample B powder 17 is filled on top of the mixed powder 16.

From the degassing pipe 19 of this powder billet, 1×
Vacuum degassing at 10-2 mmHg was performed at 400° C. for 1 hr and the container was sealed. This powder billet was put into an electric furnace for 1200
After heating to ℃, the extrusion ratio was 7 using a Eugene hot extruder.
A tube was produced by molding at an extrusion temperature of 1150°C.

The tube thus obtained was machined to remove the low carbon steel container. The joint characteristics of the pipes obtained in this manner were evaluated according to the test Run No. 2 shown in Table 2. 9.

[0049]

[Table 1]

[0050]

[Table 2]

Next, Run No. in Table 2. The material properties were evaluated when the heating temperature, hot deformation resistance ratio, and mixed powder layer thickness were changed based on the powder composition and molding conditions of 4, and the results are summarized in Figures 4 to 6. Shown.

[0052]

According to the present invention, it is possible to easily manufacture a joint structure of functionally graded materials having different metal material properties and having a good joining interface.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an example of a powder billet of functionally graded material used in the present invention.

FIG. 2 is a longitudinal cross-sectional view of an example of a powder billet of functionally graded material used in the present invention.

FIG. 3 is a longitudinal cross-sectional view of an example of a powder billet of functionally graded material used in the present invention.

FIG. 4 is a graph summarizing the results of Examples of the present invention.

FIG. 5 is a graph summarizing the results of Examples of the present invention.

FIG. 6 is a graph summarizing the results of Examples of the present invention.

[Explanation of symbols]

Claims (5)

[Claims] 1. A method for manufacturing a joint molded body for a first member and a second member that are made of different materials, the method comprising forming a first metal composition that is the same or similar to that of the first member to a second member that is the same or similar to that of the second member. 1. A method for manufacturing a joint molded article for dissimilar materials, comprising forming a powder-filled layer having a metal composition that changes stepwise or continuously up to a two-metal composition, and then extruding the powder-filled layer. 2. The method according to claim 1, wherein the joint molded body is a rod or a tube, and the metal composition thereof changes continuously or stepwise in the axial direction. 3. A hot deformation resistance ratio between the first metal composition and the second metal composition is 1.5 or more.
Method described. 4. Heating the powder packed bed from 70% or more of the lower solidus temperature of the first metal composition and the second metal composition to a temperature below the solidus temperature, The method according to any one of claims 1 to 3, wherein hot extrusion molding is carried out. 5. The powder-filled layer has a three-layer structure of a first metal composition, a second metal composition, and a mixed metal composition of these first and second metal compositions, and the thickness of the filled layer made of the mixed metal composition is 5. The method according to claim 1, wherein: 2 mm or more.